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Submersible Water Pumps and Float Switches for Efficient Ponds and Sumps

Updated: Jul 19, 2023

Submersible water pumps are popular among homeowners and businesses, who treasure their versatility and efficiency. As the name suggests, these pumps can completely submerge in water, making them ideal for steep pumping from a height. In contrast, surface self-priming pumps are limited by Toricelli law. Submersible pumps can drain flooded areas, irrigate gardens, remove waste water, create water features, and more. The float switch is a key component in automation, turning the pump on and off, preventing flooding and protecting the pump from damage.

In this article we will look at the different types of submersible pumps, their basic characteristics and the use of float switches in pump control. We will also give tips on choosing the right pump for your needs, installing and maintaining the pump system, and ensuring efficient pump control for ponds and sumps. Let's take the plunge!

Submersible Water Pumps and Float Switches for Efficient Ponds and Sumps

Table of Contents:

Understanding the different types of submersible pumps

a. Drainage pumps

A drain pump is designed to remove water from shallow areas such as puddles or small storage tanks. They are inexpensive, lightweight and portable, making them ideal for homeowners needing temporary drainage solutions. Drainage pumps can remove water to a few millimetres depth, ensuring the area remains dry and safe.

Foras  Drainage pump SP-SPV Series

If you need to pump dirty water use SPV:

b. Sump pumps

Sump pumps are specially designed to cope with water that accumulates in a sump, usually located in the basement or cellar, or surface water that accumulates in a bypass drainage sump near the foundation of a house. They help prevent flooding and water damage by automatically switching on when the water level in the pit reaches a certain height. Sump pumps are essential for homes and businesses located in areas prone to heavy rainfall or high groundwater levels.

Foras DC - Drainage pump with a set-back Vortex type

c. Pond pumps

These pumps are used to circulate and oxygenate water in ponds, water features and fountains. They help maintain a healthy ecosystem by preventing algae growth and promoting the well-being of fish and other aquatic life. Pond pumps are available in various sizes and capacities, depending on the size of the pond and the desired flow rate.

Foras DR drainage pump

d. Dirty water pumps

Dirty water pumps are designed to handle water containing solid particles such as sand, dirt or waste water. They are commonly used in construction, agriculture and wastewater management systems. These pumps are characterised by their heavy-duty construction and their ability to handle solids, enabling them to move dirty water efficiently without clogging or damage.

Foras DB Series Link

Foras FC Series Drainage pump for loaded waters with open ring impeller

e. Pumps for clean water

These pumps are designed for pumping clean or slightly dirty water, e.g. rainwater or groundwater from wells. They are normally used for domestic applications such as garden irrigation and water supply. Pumps for clean water often have less capacity to pump solids than pumps for dirty water, making them unsuitable for pumping heavily contaminated water.

Multistage drainage pump for clean water Foras SPM

f. Pumps for industry and commercial building

If you need a pump for industrial applications, we recommend FTR 550 Sewage Drainage Pump. This pump is equipped with an open impeller and an advanced grinder system for shreding sewage with suspended solids, ensuring uninterrupted operation and preventing clogging. It is the perfect choice for emptying septic tanks, residential sumps, rainwater systems, and draining flooded areas. The quick coupling feet DN50 and DN65 are available for easy installation of flanged pumps.

Foras FTR-FTRT Series  Centrifugal drainage pumps

Key Features of high-quality submersible water pumps

a. Flow rate

The flow rate, measured in litres per minute (LPM) or gallons per minute (GPM), indicates how much water a pump can move in a specific time period. A higher flow rate is important for applications that require large volumes of water to be moved quickly, such as draining flooded areas or supplying water for irrigation.

b. Lift height (head)

Head refers to the vertical distance over which the pump can move water. High head is decisive when water needs to be pumped uphill or over long distances. Pumps with a high head are usually equipped with a more powerful motor and a larger impeller(s), allowing them to move water more efficiently.

c. Heavy duty design

A high-quality submersible electric pump from a renowned European manufacturer should be chosen for permanent operation under harsh conditions. In contrast to the many cheap copies from the Far East, the pump must have a rugged, waterproof construction to withstand the harsh conditions of immersion in water. Look for pumps made from durable materials such as stainless steel, cast iron or reinforced thermoplastic. These materials can resist corrosion, wear and damage from particles and debris.

d. Abrasion resistance

Solids handling capacity indicates the maximum size of solids the pump can handle without clogging or damaging the impeller. Dirty water pumps generally have a higher solids-handling capacity than clean water pumps, allowing them to move water with coarse debris or sewage.


The importance of float switches in pump control

a. Manual and automatic operation

Float switches are required to control the operation of a submersible pump. They are used to switch the pump on and off automatically. In contrast to manual operation, where the user has to switch the pump on manually when required, with automatic operation the float switch activates the pump when the water level reaches a predetermined height and consequently switches it off when the water level drops to the required height. Automatic operation is useful for preventing flooding and maintaining a constant water level in ponds and cesspools.

b. Drainage pump float switch operating principle

A float switch is a mechanical switch that floats on the surface of the liquid. When the liquid level rises or falls, it moves vertically with the liquid level. A float switch consists of a hollow floating body and an internal switch. The most common internal switch is a reed switch, so there is also a magnet inside the body. Float switches with an external counterweight have defined tripping angles. The cable length from the counterweight to the float switch is therefore an angle with the water level. These switches have a minimum and maximum cable length to adjust to the vessel geometry. Consequently, they can be set differently if they are used to start or stop the pump. There are different types of switches, but the principle is the same depending on the water level, moving the float switch vertically up or down. Thus, the mechanical float switch automatically opens or closes the electric circuit of the submersible pump.

 Drainage pump float switch operating principle
1 - steel cable; 2 - switch-off level; 3 - float switch; 4 - switching level.

Installation and maintenance of a submersible pump system

a. Correct connection and setting

Correct installation is decisive for the efficient operation of the submersible pump system. Make sure that the pump is securely connected to the hose or pipe and that the electrical connection is securely connected to a socket or other power source. Follow the manufacturer's recommendations for proper installation and setting.

b. Accounting for hoses, pipes and pressure

When selecting hoses or pipes for the pump system, consider the required flow, head and pressure. The hoses and pipes must be of the correct size and material to withstand the required flow and pressure without leakage or damage. Also make sure that the hoses and pipes are securely connected to the pump and to any other fittings or fixtures.

c. Addressing common problems

Regular inspection and maintenance can help prevent and solve common problems with the submersible pump system. Some common problems include clogged impeller, damaged hoses or pipes and electrical problems. Refer to the manufacturer's manual for troubleshooting and maintenance procedures.

Tips for efficient pond and sump pump management

a. Regular inspections and maintenance

Regular inspections and maintenance are critical to ensure effective operation of the pond and sump pump systems. Check that there is no debris or blockage in the pump and hoses, clean the impeller if necessary, and make sure all connections are secure and in good condition. Replace any damaged or worn components if necessary.

b. Water level and flow rate monitoring

Keeping an eye on the water level and flow rate will help you identify any problems or inefficiencies in your pumping system. Monitor the water level in your pond or sump and adjust the float switch settings as necessary to maintain the correct water level. If you notice significant changes in flow rate, check the pump for blockages or damage.

c. Ensuring optimum pump performance

To maintain optimum pump performance, be sure to select a pump for your specific needs and keep it clean and tidy. Inspect the pump regularly for wear and tear or damage and replace components as necessary. Also ensure that the pump is securely connected to hoses, pipes and power sources.

Our Top 5 Submersible Water Pump and Float Switch

There are many high quality submersible water pumps and float switches on the market. Consider factors such as flow rate, head, ability to handle solids and construction materials when selecting a pump and float switch. Read product reviews and manufacturer information to find the best pump and float switch for your specific needs and application.


Foras SPM 3/4G

Garden irrigation (high head and high capacity)



​Flooded premises and drainage (capable of pumping from a flat surface to a water level of 1mm)



​Wastewater management (has a grinder on the inlet for shredding the solid fraction)



​Water bodies and ponds (pumps solids up to 6 mm)



​Heavy Duty (Special Design allows the pump to run for hours without water and pumps solids up to 6 mm)

Conclusion: Maximise efficiency with submersible water pumps and float switches

Submersible water pumps and float switches provide a versatile and effective solution for a variety of water management tasks, from draining flooded areas to maintaining healthy ponds and water features. Understanding the different types of submersible pumps, their key features and the importance of float switches in pump control is crucial to choosing the right pump system for your needs.

When selecting a submersible pump, consider factors such as flow rate, head, ability to handle solids and construction materials. Selecting a reliable pump for your application can ensure optimum performance and prevent problems such as clogging, damage or flooding.

Correct installation, maintenance and troubleshooting will help keep the submersible pump system working efficiently. Inspect the pump, hoses and connections regularly for wear or damage and replace any components as necessary. Monitor the water level and flow rate to detect any faults or problems in the system.

In conclusion, submersible water pumps and float switches are a reliable and efficient solution for various water management tasks. By choosing a reliable pump for your application and maintaining it correctly, you can maximise efficiency and prevent problems for years to come.


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